1. Field of the Invention
The present invention generally relates to glass or glass ceramic articles which are provided with an opaque coating. More particularly, the invention relates to such articles which are provided with light-emitting display elements or intended to be equipped with light-emitting display elements.
2. Description of Related Art
From the prior art, glass ceramic cooktops are known which are coated on their lower surface in order to modify the appearance and to conceal parts of the cooktop installed below the glass ceramic.
One option for this purpose are sol-gel coatings which are quite heat resistant and are distinguished by good adhesion to the glass ceramic plate. For concealing internal parts of a cooktop, opaque coatings are typically used.
For some applications it is desirable that the coating does not cover the entire surface but has windows. Such windows are in particular arranged in front of light-emitting display elements, so that these display elements shine through the glass ceramic plate to be visible to an operator which looks at the utilization side of the cooktop. Partly, these windows are covered by translucent coatings to improve aesthetic appearance. With the same hue, a homogeneous surface is created in this manner.
Nowadays, icons, characters, or other logos and designs are printed on cooktops by screen printing. However, it is difficult in this case to produce very fine patterns such as thin lines, for example.
Moreover, concerning screen printing, reproducibility is difficult in areas of very fine resolution or runouts of lines due to the screen printing mesh. Furthermore, for every new product request or design change a new screen needs to be created, so that set-up costs are very high, which is especially noticeable in small series. Manufacturing of individual designs for each end user is therefore expensive.
Furthermore, as to multilayer coatings, in case of a printing technique such as screen printing the problem arises that congruent patterning is difficult. Therefore, in case of multilayer coatings usually a larger window is omitted, to allow to pattern a further coating layer with exactly the desired pattern in the area of the window. However, especially in combination with light-emitting display elements the window might be visible if the more precisely patterned coating layer is not completely opaque.
EP 0 868 960 B1 discloses a method for manufacturing control panels, in particular for electrical household appliances, wherein at least one personalized laser engraving is produced in at least one screen printed layer which has previously been applied to a basic panel blank, the engraving consisting in material removal so as to form decorative features, icons, or similar signs in the screen printed layer, and then these engravings are covered by manually or automatically applying a layer of different color, which may be effected immediately after the engraving step or in a separate operation.
With regard to design aspects, it would moreover be especially desirable that the windows in the coating, which allow the light from the display elements to pass therethrough are as visually inconspicuous as possible. A seemingly homogeneous surface in which the display features are invisible in the off state would be ideal.